1. Field of the Invention
The present invention relates to a self diagnostic apparatus of a vehicle information display system such as an instrument panel of a vehicle for displaying vehicle information thereof.
2. Discussion of Related Arts
A vehicle has a vehicle information display system, for example, an instrument panel, for displaying miscellaneous information of the vehicle, incorporating a speed meter, an engine tachometer, a fuel level gauge, a water temperature indicator, an odometer, a trip meter and the like therein. The vehicle information display system (hereinafter referred to as an instrument panel) inputs various information from the vehicle through dedicated signal wires, serial transmission lines and the like and the self diagnosis for the instrument panel is performed based on this inputted information.
In thus constituted instrument panel, in order to perform diagnoses of the instrument panel, that is, in order to check for abnormal operation of a pointer of a meter, abnormal lighting of a lighting system and the like, miscellaneous signals are inputted from the vehicle through dedicated signal lines, serial transmission lines and self diagnoses of the instrument panel are performed based on these inputted signals.
However, in the aforesaid instrument panel having self diagnostic functions, since the self diagnoses are performed based on miscellaneous signals inputted from the vehicle through the dedicated signal lines or serial transmission lines, the instrument panel can not perform self diagnoses by itself, that is, in a condition of those lines disconnected from the vehicle.